<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<title></title>
	<link rel="stylesheet" href="">
</head>
<body>
	<script>
		let obj = []
		function isArray(obj) {
			return obj.__proto__ === Array.prototype;
		}
		alert(isArray(obj))
	</script>
</body>
</html>